Process of coating glass with durable coatings and resulting products

ABSTRACT

A glass coating composition comprising 30 to 57 parts by weight of a butylated urea formaldehyde, 10 to 35 parts by weight of a partially hydrolyzed copolymer of vinyl acetate and vinyl chloride, and 27 to 45 parts by weight of a hydrogenated furfuraldehyde ketone useful in the application of decorative coatings to glass articles and the like, including various types of electrical lamps wherein a colorful effect is obtained.

United States Patent Sierad 1 Feb. 29, 1972 [72] Inventor: Theodore B.Sierad, Harrison, NY.

[73] Assignee: The Brudenell Corporation, Port Washington, N.Y.

[22] Filed: Sept. 4, 1970 [21] Appl. No.1 69,962

[52] U.S.Cl. ..117/71 R, 117/72, 117/94, 117/124 E, 260/851 [51] Int. Cl..C03c 17/32, C23c 3/02 [58] Field of Search ..117/71 R, 72, 124 E;260/851 [56] References Cited UNITED STATES PATENTS 2,607,750 8/1952Wilson et a1. ..260/851 X 2,650,184 8/1953 Biefeld......... ..117/72 X2,884,342 4/1959 Wolff ..2'60/851 X 2,917,439 12/1959 Liu ..117/71 R X2,956,902 10/1960 Greif ..260/851 X 3,024,216 3/1962 Smitmans et a1..117/124 E X 3,183,282 5/1965 Hurwitz ....260/85l X 3,214,286 /1965Ramberger ..117/72 X 3,479,198 11/1969 Barth ..117/72 X 3,515,579 6/1970Shepherd et al ..117/124 E Primary Examiner-Alfred L. Leavitt AssistantExaminer-J. R. Batten, Jr. Attorney Darby & Darby [57] ABSTRACT A glasscoating composition comprising to 57 parts by weight of a butylated ureaformaldehyde, 10 to parts by weight of a partially hydrolyzed copolymerof vinyl acetate and vinyl chloride, and 27 to parts by weight of ahydrogenated furfuraldehyde ketone useful in the application ofdecorative coatings to glass articles and the like, including varioustypes of electrical lamps wherein a colorful effect is obtained.

8 Claims, No Drawings PROCESS OF COATING GLASS WITH DURABLE COAT TNGSAND RESULTING PRODUCTS This invention relates to glass coatingcompositions. More particularly this invention relates to a durableglass coating composition useful in the application of decorativecoatings to glass. Still more particularly this invention relates to adurable glass coating composition useful in the application ofdecorative metallic-appearing coatings to incandescent light bulbs.

It is well known in the prior art to provide decorative coatings on theexterior glass surfaces of various glass fixtures including electriclamps. For example, decorative coatings have been applied to varioustypes of incandescent lamps for use as Christmas tree ornaments anddecorative lights. Various lacquers and silvering compositions have beencoated onto the exterior surfaces of incandescent lamps to provide thesedecorative effects. These decorative coatings are subject to handlingand intense heat radiated from the incandescent lamp, and it has beenfound that the prior art coatings have a tendency to chip, crack or peelafter relatively short use. Another problem encountered in applyingdecorative coatings to the exterior surfaces of incandescent lamps, aswell as other glass articles, is the difficulty in securing goodadherence of the coating to the generally glossy surface to provide auniform uninterrupted coating without chips, cracks, or pinholes. Tothis end, the prior art has utilized intermediate compositions as basecoatings applied to the glass substrate upon 'which the decorativecoating could be more uniformly applied, thereby attempting to provideimproved appearance and durability.

The prior art has utilized nitrocellulose, as well as oleoresinous-typecoatings as intermediate compositions for the glass substrate upon whichdecorative silver and lacquer coatings have been applied. Althoughproviding improved coating qualities, these intermediate compositions donot provide improved coating durability, since they are affected by theconstant temperature humidity change incident to operation of the lampand begin to chip off after a few months, carrying the decorativematerial with them.

It is an object of this invention to provide a coating compositionuseful as a base coating in the application of decorative coatings toglass surfaces.

Another object is the provision of a coating composition useful as abase coating in the application of decorative coatings to incandescentlamps.

A further object is the provision of a decorative coating for glasssurfaces.

A still further object provides a process for applying the novel coatingcompositions of this invention.

The foregoing and other objects will be apparent from the followingdescription of the invention.

The novel compositions of this invention which are particularly usefulfor coating glass comprise 30-57 parts by weight of butylated ureaformaldehyde, -35 parts by weight of a partially hydrolyzed copolymer ofvinyl acetate and vinyl chloride, and 27-45 parts by weight of ahydrogenated furfuraldehyde ketone. This composition is applied as abase coat to a glass substrate, and a decorative coating subsequentlyapplied thereupon. An optional top coating can be applied over thedecorative coating. All weights are given by dry weight, it beingunderstood that most of the components of this composition are providedin solution.

The amount of hydrogenated furfuraldehyde ketone used in the compositiondetermines the curing time of the base coating. When a greater amount isused, a longer curing time will be required. However, a tougher coatingwill result The curing time as well as the solids content of the basecoating may be varied by increasing or decreasing the amount ofpartially hydrolyzed vinyl copolymer used in the base coatingcomposition. When a higher amount of the partially hydrolyzed vinylcopolymer is employed in the base coating composition, the curing timewill be reduced; however, the coating will not be as glossy and willcontain less solids.

A wide range of organic solvents may be used alone or in a solvent blendfor applying the cross-linkable base layer of this invention. Suitablesolvents include ethylene glycol monoethyl ether, methyl isobutylketone, methyl ethyl ketone, methyl iso-amyl ketone or hydroxy ethylacetate. Aromatic solvents and aliphatic naphtha solvents have adeleterious effect upon subsequent silvering processes and they shouldnot be employed if such processes will be employed to provide thedecorative coating.

A catalyst solution useful in the preparation of the base coatingcomposition is made by mixing 10-40 parts by volume of concentratedhydrocholric acid with 128 parts by volume of ethylene glycol mono-ethylether. An amount of catalyst solution equal to 25-75 percent ofthe drysolids weight of the base coating composition is added. just prior touse. The entire batch of base coating composition should be used within40 minutes of the addition of the catalyst solution. The resistance ofthe base coating to chipping and peeling may be increased by increasingthe amount of acid from 10 to 40 parts in this catalyst solution. Itshould be noted, however, that this will result in a hazing or burningof the final decorative coating, and may not be desirable in allapplications.

A preferred process for using the coating composition in making adecorative glass article is described below. The base coatingcomposition of this invention is prepared in advance and applied byeither spray or dip coating onto a glass surface to be decorativelycoated. It is advisable that the base coating composition be used within40 minutes of its preparation to achieve maximum coating regularity,uniformity and durability. The base coating may be applied in either onelayer or a plurality of layers, the thickness of each layer preferablyranging from 0.001-0.002 inches.

After coating with the base layer, the glass article is cured in anoven. The first layer of base coating is dried in an oven for l to 2minutes at 200 F. and then ideally air cooled for 30 seconds at roomtemperature. If a second layer of base coating is used, it is appliedover the dried first layer with approximately the same thickness as thefirst layer, and the glass article again cured in a clean air-oven at atemperature of 325-390 F. for l to 2 minutes. The article is again aircooled for at least 30 seconds.

An appropriate decorative coating such as metallic film of silver orgold, or aluminum is then applied to the cured base coating. Suitableprocessesf for applying silver coatings to the base coating compositionsof this invention are well known in the trade and are described inUnited States Department of Commerce Technical Bulletin No. BD-11236,Silver Film by Samuel Weir.

After the decorative coating has been applied, the glass article isblown dry with a dust and oil-free jet of air, and then spray coatedwith a top coating composition designed to serve as a protective film. Asuitable top coating composition comprises l 1 parts by weight of apartially hydrolyzed copolymer of vinyl chloride and vinyl acetate(VAGH-Bakelite Div., Union Carbide), 6-12 parts by weight of athermosetting acrylic polymer (ATSl Rohm & Haas) in a suitable solventsuch as methyl isobutyl ketone. Use of aliphatic naphtha and aromaticsolvents should be avoided due to a deleterious effect on decorativesilver coatings. A solvent such as dimethylformamide may be optionallyemployed in applying the top coating as a coating aid andto prevent pinholes. The properties of the top coating may be changed somewhat to suitindividual applications by varying the amount of thermosetting acrylicpolymer in the coating composition. Higher amounts of polymer tend toimprove the adhesive qualities of the top coating, while lower amountsyield a coating having improved resistance to humidity. An appropriatecolor dye, e.g., 2-RB percent Blue, Orange-G, etc., can also be includedin the top coating to provide various color effects. The thickness ofthe top coating ranges between 0.0005 and 0.001 inch.

After the top coating has been applied, the glass article is air driedfor 45 seconds and may then be handled.

The coated article is finally baked in an oven for a period of 15 to 45minutes at a temperature of 240-310 F., the exact time and temperaturedepending upon the materials used and the specific results desired inthe final product.

The decorative coating compositions of this invention are durable andresistant to chipping and peeling as well as variations in temperatureand humidity. They are particularly useful in the decoration ofincandescent lamps and other glass articles which are subjected tohandling or temperature extremes, e.g., ashtrays.

The invention will be further illustrated by, but is not intended to belimited to, the following examples:

EXAMPLE 1 A suitable base coating composition was prepared by mixingtogether 45 grams of a hydrogenated furfuraldehyde ketone in a suitablesolvent (Furatone B2 50 percent solids produced by Minnesota Mining &Manufacturing Company), 28 grams of a partially hydrolyzed copolymer ofvinyl acetate and vinyl chloride (VAGl-l Bakelite Div. Union Carbide)dissolved in 1265 grams of 18 percent methylisobutyl ketone; (thecopolymer is 89.5-91.5 percent vinyl chloride, and l.55.2 percent vinylacetate by weight), and 56.5 grams of butylated urea formaldehyde in asuitable solvent (Rohm & Haas UF 240 60 percent solids) is blended in 37grams of methyl isobutyl ketone and 42.5 grams of 2 ethoxy ethanol. Acatalyst solution was prepared by mixing 40 ml. of concentratedhydrochloric acid and 128 ml. of 2 ethoxy ethanol in a separatecontainer. Thirty-six grams of the catalyst solution was added to thebase coating composition immediately before the composition was spraycoated to a depth of 0.001 inch onto the envelopes of a number of50-watt incandescent lamps. The entire coating composition was usedwithin 5 minutes of the addition of the catalyst solution to the coatingcomposition. The incandescent lamps were then cured in a hot-air ovenfor 2 minutes at 300 F., air cooled at room temperature for 30 secondsand recoated with the same base coating mixture and then cured in aclean hot-air oven at 325 for 1% minutes.

A decorative silver metal coating was applied by first spraying thecoated lamps with 25 percent solution of sodium di-(2 ethyl hexyl)phosphate (Triton N.E. manufactured by Rohm & Haas), and then a solutionof stannous chloride. The lamps were then treated with a warm deionizedwater rinse and coated with a two-part solution mixed immediately priorto application consisting of parts by weight of ammoniated silvernitrate and 1 part by weight of hydrazine reducer. The lamp was finallyrinsed with warm deionized water.

A top coating composition was prepared by mixing 1 1 grams of the vinylcopolymer resin dissolved in 56.5 grams of 18 percent methyl isobutylketone with 8.5 grams of a thermosetting acrylic polymer (Rohm & HaasAT51) and 40.2 grams of methyl isobutyl ketone, 16 grams ofdimethylformamide and 0.1 grams of 2-RB 80 percent blue dye manufacturedby Rohm & Haas. After the top coating of the lamp was blown dry, with aclean air jet, they were spray-coated to a depth of approximately 0.0005inch with the thus prepared top coating composition. After air dryingfor 45 seconds the lamps were baked in a hot-air oven at 250 F. for 20minutes.

EXAMPLE 2 A number of 50-watt incandescent lamps similar to those usedin Example 1, were coated in a similar fashion using a base coatingcomposition containing 45 grams hydrogenated furfuraldehyde ketone, 16grams of a partially hydrolyzed copolymer of vinyl chloride and vinylacetate as used in Example 1; this composition was blended in 72 gramsof methyl-isodescent lamp, when the filament is energized, there is anapparent change in color of the coating, thereby providing anadditional, pleasing, aesthetic effect.

What is claimed is: 1. A coated element comprising a glass base, across-linkable base layer coated on one surface of said base comprising30 parts by weight of butylated urea formaldehyde, 45 parts by weight ofhydrogenated furfuraldehyde ketone, and 16 parts by weight of apartially hydrolyzed copolymer of vinyl chloride and vinyl acetate.

2. A coated element as recited in claim 1, further including adecorative coating comprising a thin layer of metallic silver coated onsaid base coating.

3. A coated element as recited in claim 2, further including aprotective top coating comprising 8.5 parts by weight of a thermosettingacrylic polymer, 11 parts by weight of a partially hydrolyzed copolymerof vinyl chloride and vinyl acetate, and 0.1 part by weight of a dyecomposition.

4. A process for applying a decorative coating composition on a glasssurface comprising the steps of coating said glass surface with across-linkable base coating composition comprised of 45 parts by weightof a hydrogenated furfuraldehyde ketone, 28 parts by weight of apartially hydrolyzed copolymer of vinyl acetate and vinyl chloride and56.5 parts by weight of a butylated urea formaldehyde, curing saidcoated glass surface for l to 2 minutes at 200 F., cooling said coatedglass surface for 30 seconds at room temperature, applying a thindecorative coat of metallic silver on said base coating, coating saidthin metallic layer with a protective top coating, and baking saidcoating article for 15-45 minutes at a temperature of 2403 10 F.

5. A process for applying a decorative coating to a glass article asrecited in claim 4, including the further step of admixing said ketone,said copolymer and said formaldehyde resins and adding an amount equalto 25-75 percent of the weight of said resins of a catalyst compositionwhich comprises 10-40 parts by volume of hydrochloric acid and 128 partsby volume of ethylene glycol mono-ethyl ether, and applying said basecoating composition within 40 minutes of adding said catalyst.

6. A process as recited in claim 5, including the further steps ofproviding a protective top coating composition comprising 1 1 parts byweight of a partially hydrolyzed copolymer of vinyl acetate and vinylchloride and 8.5 parts by weight of a thermosetting acrylic resin, andcoating said protective top coat to a height of 0.0005-0001 inch on saiddecorative metallic coating material.

7. A process as recited in claim 6, including the step of limiting thedepth of said base coating to 0.001-0.002 inch.

8. A process as recited in claim 7, including the further step ofapplying a second layer of said base coating composition and curing saidcoated glass article in a clean-air oven at a temperature of 325390 F.for l to 2 minutes, and spraying said base coating with a two-partsolution consisting essentially of ammoniated silver nitrate, andhydrazine to deposit a silver coating.

2. A coated element as recited in claim 1, further including adecorative coating comprising a thin layer of metallic silver coated onsaid base coating.
 3. A coated element as recited in claim 2, furtherincluding a protective top coating comprising 8.5 parts by weight of athermosetting acrylic polymer, 11 parts by weight of a partiallyhydrolyzed copolymer of vinyl chloride and vinyl acetate, and 0.1 partby weight of a dye composition.
 4. A process for applying a decorativecoating composition on a glass surface comprising the steps of coatingsaid glass surface with a cross-linkable base coating compositioncomprised of 45 parts by weight of a hydrogenated furfuraldehyde ketone,28 parts by weight of a partially hydrolyzed copolymer of vinyl acetateand vinyl chloride and 56.5 parts by weight of a butylated ureaformaldehyde, curing said coated glass surface for 1 to 2 minutes at200* F., cooling said coated glass surface for 30 seconds at roomtemperature, applying a thin decorative coat of metallic silver on saidbase coating, coating said thin meTallic layer with a protective topcoating, and baking said coating article for 15-45 minutes at atemperature of 240*-310* F.
 5. A process for applying a decorativecoating to a glass article as recited in claim 4, including the furtherstep of admixing said ketone, said copolymer and said formaldehyderesins and adding an amount equal to 25-75 percent of the weight of saidresins of a catalyst composition which comprises 10-40 parts by volumeof hydrochloric acid and 128 parts by volume of ethylene glycolmono-ethyl ether, and applying said base coating composition within 40minutes of adding said catalyst.
 6. A process as recited in claim 5,including the further steps of providing a protective top coatingcomposition comprising 11 parts by weight of a partially hydrolyzedcopolymer of vinyl acetate and vinyl chloride and 8.5 parts by weight ofa thermosetting acrylic resin, and coating said protective top coat to aheight of 0.0005-0.001 inch on said decorative metallic coatingmaterial.
 7. A process as recited in claim 6, including the step oflimiting the depth of said base coating to 0.001-0.002 inch.
 8. Aprocess as recited in claim 7, including the further step of applying asecond layer of said base coating composition and curing said coatedglass article in a clean-air oven at a temperature of 325*-390* F. for 1to 2 minutes, and spraying said base coating with a two-part solutionconsisting essentially of ammoniated silver nitrate, and hydrazine todeposit a silver coating.